MB Profile Modular Back-Up for PolyPaks and U-Cups | Zatkoff

MB Profile Modular Back-Up for PolyPaks and U-Cups

MB Profile Modular Back-Up for PolyPaks and U-Cups


Modular back-ups, MB profile, are specifically designed to compliment the PolyPak profiles. To help make the selection and ordering of the correct part number for the MB profile easy and efficient, the part numbering system used is very similar to that of the PolyPak. By formulating high modulus blends of Molythane (4617) and PolyMyte (4652), Parker has ensured that MB back-ups can be used with either type of base sealing material while maintaining the expected temperature range and fluid compatibility. The robust design ensures pressure ratings up to 10,000 psi are met.

Back-up rings are the most common anti-extrusion devices in dynamic sealing. They provide simple solutions to safely increase system pressure or solve an existing seal extrusion problem. Back-up rings function by positioning a more robust material adjacent to the extrusion gap, taking the seal’s place and providing a barrier against high pressures. Back-ups can be used to offset the reduced pressure rating effects of wear rings or to improve seal life at increased pressures. They can also be used to protect seals against pressure spikes, or to ensure seal performance at higher temperatures.


When to Use Back-up Rings

  • System operating pressure exceeds the limitations of the seal’s extrusion resistance.
  • Pressure spikes in the system exceed normal operating conditions,risking damage to the seal.
  • The use of wear rings has increased the extrusion gap, reducing the seal’s pressure rating to an unacceptable level.
  • The system temperature is high enough to lower the seal’s extrusion resistance to an unacceptable level.

Standard Materials

  • P4617D65
  • Z4652D65